In parent application Ser. No. 447,688, whose entire disclosure is incorporated herein by reference, commutation circuits are disclosed for a brushless D.C. motor, the exemplary motors having two independently energizable windings and per rotor rotation each winding receiving one respective current pulse; or else the winding consists of a single winding but per rotor rotation a first pulse of current is passed through the winding in one direction and then a second pulse in the opposite direction. In both instances there are two winding current paths each containing at least one power transistor switch controlled by a driver transistor switch; when the driver transistor switch assumes its high-output-impedance state the respective power transistor switch is rendered conductive, and when it assumes its low-output-impedance state the respective power transistor switch is rendered non-conductive. Also, the circuits illustrated in the parent case are provided with means for delaying switch-on of the power transistor switches, such that in the course of commutation it does not happen that the power transistor switches in both winding current paths are in conductive state simultaneously.
Although these circuits satisfactorily perform their intended functions, it has been found that they can in advantageous ways be further simplified.